Charged particle beam instrument and sample container

ABSTRACT

A charged particle beam instrument is offered which can introduce cooled samples easily into a sample chamber. The charged particle beam instrument ( 100 ) of the present invention has: a sample container ( 10 ) that accommodates samples (S) and a refrigerant ( 6 ) for cooling the samples (S); an evacuated sample chamber ( 20 ); a sample exchange chamber ( 30 ) connected with the sample chamber ( 20 ); a partition valve ( 40 ) disposed between the sample exchange chamber ( 30 ) and the sample container ( 10 ); and vacuum pumping equipment ( 50 ) for evacuating the sample container ( 10 ). The sample container ( 10 ) can be connected with the sample exchange chamber ( 30 ) via the partition valve ( 40 ). The sample container ( 10 ) is evacuated by the vacuum pumping equipment ( 50 ) while the partition valve ( 40 ) is closed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a charged particle beam instrument anda sample container.

2. Description of Related Art

Where a sample is observed with a charged particle beam instrument suchas an electron microscope, if the sample is a biological sample or apolymeric material, and if the sample is irradiated with a chargedparticle beam (such as an electron beam), the structure of the samplemay be destroyed and thus the sample under normal conditions may not beobserved. In this case, where the sample is cooled below the temperatureof liquid nitrogen (for example, a cryogenic temperature), even if thesample is irradiated with a charged particle beam such as an electronbeam, the sample will be destroyed less easily. The sample under normalconditions can be observed.

However, when a sample is cooled and introduced into a sample chambersuch as of an electron microscope that is in a vacuum state, variouscontrivances have been made to prevent crystalline ice or frost frombeing deposited on the sample (see, for example, JP-A-2013-037841).

SUMMARY OF THE INVENTION

The present invention has been made in view of the foregoing problems.One object associated with some aspects of the present invention is toprovide a charged particle beam instrument permitting cooled samples tobe introduced into a sample chamber easily.

Another object associated with some aspects of the invention is toprovide a sample container capable of introducing cooled samples into achamber of a charged particle beam instrument easily.

(1) A charged particle beam instrument associated with the presentinvention has: a sample container that accommodates samples and arefrigerant for cooling the samples; an evacuated sample chamber; asample exchange chamber connected with the sample chamber; a partitionvalve disposed between the sample exchange chamber and the samplecontainer; and vacuum pumping equipment for evacuating the samplecontainer. The sample container can be connected with the sampleexchange chamber via the partition valve. The sample container isevacuated by the vacuum pumping equipment while the partition valve isclosed.

In this charged particle instrument, the sample container is evacuatedby the vacuum pumping equipment while the partition valve is closed.Therefore, the partition valve can be opened after the interior of thesample container is evacuated and the refrigerant is solidified.Consequently, the samples can be introduced into the sample exchangechamber from the sample container even if the refrigerant is left in thesample container. This facilitates insertion of the cooled samples intothe sample chamber.

(2) In one feature of this charged particle beam instrument, the samplecontainer may have a sample-receiving space for receiving the samples, arefrigerant-receiving space for receiving the refrigerant, and athermally conductive member that partitions the sample-receiving spaceand the refrigerant-receiving space from each other. The thermallyconductive member may be provided with communication holes for placingthe sample-receiving space and the refrigerant-receiving space incommunication with each other.

In this charged particle beam instrument, if the sample container isevacuated and the refrigerant solidifies, it is possible to preventadhesion of the solidified refrigerant onto the samples.

(3) In another feature of this charged particle beam instrument, thesample exchange chamber may have a sample storage portion capable ofholding the samples. There may be further provided a cooling portion forcooling the sample storage portion.

In this charged particle beam instrument, the samples can be kept in thesample exchange chamber while being cooled.

(4) In a further feature of this charged particle beam instrument, theremay be further provided first and second transfer rods. The firsttransfer rod conveys the samples between the sample container and thesample exchange chamber. The second transfer rod conveys the samplesbetween the first transfer rod and the sample storage portion.

In this charged particle beam instrument, the samples can be conveyedfrom the sample container into the sample storage portion, and viceversa.

(5) In a still other feature of this charged particle beam instrument,the second transfer rod may operate to convey the samples between thesample storage portion and the sample chamber.

In this charged particle beam instrument, the samples can be conveyedeither from the sample container or from the sample storage portion intothe sample chamber, and vice versa.

(6) In an additional feature of this charged particle beam instrument,the refrigerant may be evacuated by the vacuum pumping equipment andbecome solidified.

In this charged particle beam instrument, the cooled samples can beeasily introduced into the sample chamber.

(7) In a still further feature of this charged particle beam instrument,the refrigerant may be any one of liquid nitrogen, liquid methane,liquid ethane, and liquid butane.

In this charged particle beam instrument, the refrigerant can besolidified by evacuating the sample container. This permits the cooledsamples to be introduced into the sample chamber easily.

(8) Another charged particle beam instrument associated with the presentinvention has: an evacuated sample chamber; a sample exchange chamberconnected with the sample chamber; a sample storage portion formed inthe sample exchange chamber and capable of holding samples therein; anda cooling portion for cooling the sample storage portion.

In this charged particle beam instrument, the samples can be kept in thesample exchange chamber while being cooled. Therefore, the cooledsamples can be easily introduced into the sample chamber.

(9) A sample container associated with the present invention can beconnected via a partition valve with a sample exchange chamber in acharged particle beam instrument. The sample container includes asample-receiving space for receiving samples, a refrigerant-receivingspace for receiving a refrigerant, and a thermally conductive memberthat partitions the sample-receiving space and the refrigerant-receivingspace from each other. The thermally conductive member may be providedwith communication holes for placing the sample-receiving space and therefrigerant-receiving space in communication with each other.

With this sample container, even if the sample container is evacuatedand the refrigerant becomes solidified, adhesion of the solidifiedrefrigerant onto the samples can be prevented. Accordingly, when thissample container is connected with the sample exchange chamber via thepartition valve, the refrigerant can be solidified by evacuating thecontainer while the partition valve is closed. Consequently, the samplescan be introduced into the sample exchange chamber from the samplecontainer without bringing the sample exchange chamber to atmosphericpressure. Hence, the cooled samples can be easily introduced into thesample chamber.

(10) In one feature of this sample container, the refrigerant-receivingspace is evacuated, whereby the refrigerant is solidified.

With this sample container, the cooled samples can be easily introducedinto the sample chamber.

(11) In another feature of this sample container, the refrigerant may beany one of liquid nitrogen, liquid methane, liquid ethane, and liquidbutane.

With this sample container, the refrigerant can be solidified byevacuating the sample container. This permits the cooled samples to beintroduced into the sample chamber easily.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross section, party in block form, of mainportions of a charged particle beam instrument associated with oneembodiment of the present invention.

FIG. 2 is a schematic vertical cross section of the sample containershown in FIG. 1.

FIG. 3 is a schematic perspective view of one of the cartridges shown inFIGS. 1 and 2.

FIG. 4 is a schematic perspective view of the magazine shown in FIGS. 1and 2, and in which cartridges of the structure shown in FIG. 3 havebeen mounted to the magazine.

FIGS. 5-11 are vertical cross sections similar to FIG. 1, but showingdifferent operative conditions of the charged particle beam instrumentfor illustrating the operation.

FIG. 12 is a vertical cross section, party in block form, of mainportions of a known charged particle beam instrument providing areference.

FIG. 13 is a vertical cross section of the charged particle beaminstrument shown in FIG. 1, showing other components.

DESCRIPTION OF THE INVENTION

The preferred embodiments of the present invention are hereinafterdescribed in detail with reference to the drawings. It is to beunderstood that the embodiments provided below do not unduly restrictthe scope of the present invention delineated by the appended claims andthat not all the configurations described below are essentialconstituent components of the invention.

1. Charged Particle Beam Instrument

The configuration of a charged particle beam instrument associated withone embodiment of the present invention is first described by referringto FIG. 1, which schematically shows main portions of the chargedparticle beam instrument, 100. In FIG. 1, X-, Y-, and Z-axes are shownas mutually perpendicular axes.

As shown in FIG. 1, the charged particle beam instrument 100 isconfigured including a sample container 10, a sample chamber 20, and asample exchange device 100A. In the present embodiment, it is assumedthat the charged particle beam instrument 100 is a transmission electronmicroscope (TEM). FIG. 1 shows the state in which the sample container10 has been attached to the sample exchange device 100A.

(1) Sample Container

First, the sample container 10 is described. FIG. 2 schematically showsthe sample container 10. FIG. 3 is a schematic perspective view of onecartridge 2. FIG. 4 is a schematic perspective view of a magazine 4, andin which cartridges 2 have been mounted to the magazine 4.

The sample container 10 is a receptacle for conveying cooled samples S.The samples S and a refrigerant 6 for cooling the sample S areaccommodated in the sample container 10.

As shown in FIG. 2, the sample container 10 accommodates the magazine 4to which the cartridges 2 are mounted. Each cooled sample S is held to arespective one of the cartridges 2 by an anchoring member 3 as shown inFIG. 3.

Each sample S is a biological sample or a polymeric material whosestructure is readily destroyed by a charged particle beam such as anelectron beam or ion beam.

The anchoring member 3 is configured including a C-ring or a leafspring.

Each cartridge 2 is a plate-like member provided with a through-hole.Each sample S is held in the through-hole of a respective one of thecartridges 2 with the securing member 3.

As shown in FIG. 4, the cartridges 2 are mounted to the magazine 4. Inthe illustrated example, three cartridges 2 are mounted to the magazine4. Preferably, the cartridges 2 and magazine 4 are made of a thermallyconductive material.

The samples S are cooled, for example, below the temperature of liquidnitrogen (such as a cryogenic temperature) and then held to therespective cartridges 2. The cartridges 2 on which the respectivesamples S are held are mounted to the magazine 4 and carried by thesample container 10. In the present example, the cartridges 2 on whichthe respective samples S are held are mounted to the magazine 4 andreceived in the sample container 10. Alternatively, the samples S may bedirectly received in the sample container 10 without using thecartridges 2 or magazine 4 in an unillustrated manner.

As shown in FIG. 2, the sample container 10 is configured including areceiving portion 12, a cover portion 14, and a thermally conductivemember 16.

The receiving portion 12 has a sample-receiving space 18 a and arefrigerant-receiving space 18 b. In the illustrated example, themagazine 4 to which the cartridges 2 have been mounted is received inthe sample-receiving space 18 a. The refrigerant 6 is received in therefrigerant-receiving space 18 b. As long as the receiving portion 12can have the sample-receiving space 18 a and the refrigerant-receivingspace 18 b, no restrictions are imposed on the shape or size of thereceiving portion 12. For example, the receiving portion 12 is shapedcylindrically and has a top surface with an opening and a closed bottomsurface.

The refrigerant 6 is liquid nitrogen, for example. Alternatively, therefrigerant 6 may be liquid methane, liquid ethane, or liquid butane. Norestrictions are placed on the refrigerant 6 as long as it can cool thesamples S and can be evacuated by vacuum pumping equipment 50 (describedlater) and solidified.

The cover portion 14 plugs up the opening of the receiving portion 12 tosuch an extent that, when the refrigerant 6 vaporizes and the pressureinside the sample container 10 increases beyond atmospheric pressure,the vaporizing refrigerant 6 can be expelled from between the receivingportion 12 and the cover portion 14. The cover portion 14 makes itpossible to set the pressure inside the sample-receiving space 18 a ofthe sample container 10 higher than atmospheric pressure, thuspreventing outside air including moisture from entering the samplecontainer 10. Consequently, it is possible to prevent adhesion of icecontamination (such as crystalline ice or frost) onto the samples S.

The thermally conductive member 16 partitions the sample-receiving space18 a and the refrigerant-receiving space 18 b from each other. In theillustrated example, the sample-receiving space 18 a is surrounded bythe thermally conductive member 16, receiving portion 12, and coverportion 14. The refrigerant-receiving space 18 b is surrounded by boththermally conductive member 16 and receiving portion 12. In theillustrated example, of the space partitioned by the thermallyconductive member 16 of the receiving portion 12, the sample-receivingspace 18 a is a space on the opening side of the receiving portion 12while the refrigerant-receiving space 18 b is a space on the bottom sideof the receiving portion 12.

The thermally conductive member 16 is used to transfer heat between eachsample S and the refrigerant 6. The thermally conductive member 16 ismade of a material having a high thermal conductivity such as copper.Alternatively, the thermally conductive member 16 may be made of othermetal or an alloy thereof. The magazine 4 is put on the thermallyconductive member 16, which in turn transfers heat from the magazine 4to the refrigerant 6. As a result, the samples S, cartridges 2, andmagazine 4 can be cooled.

The thermally conductive member 16 is provided with communication holes19 for placing the sample-receiving space 18 a and therefrigerant-receiving space 18 b in communication with each other. Inthe illustrated example, the communication holes 19 are two in number.The number of the communication holes 19 may also be three or more. Therefrigerant 6 can be supplied into the refrigerant-receiving space 18 bthrough the communication holes 19. Also, the refrigerant 6 in vaporizedform enters the sample-receiving space 18 a through the communicationholes 19.

As shown in FIG. 1, the sample container 10 can be connected with thesample exchange chamber 30 while a partition valve 40 is closed. In theillustrated example, the sample container 10 is connected with thesample exchange chamber 30 via a connecting member 42.

The sample container 10 is evacuated by the vacuum pumping equipment 50while the partition valve 40 is closed. Consequently, therefrigerant-receiving space 18 b is evacuated. The freezing point of therefrigerant 6 (such as liquid nitrogen) received in therefrigerant-receiving space 18 b rises and the refrigerant 6 solidifies.When the refrigerant 6 solidifies, particulates of the solid refrigerant(such as solid nitrogen) deposit and so gaps are formed among theparticulates. This gives rise to an increase in the volume. In thesample container 10, the refrigerant 6 is surrounded by the thermallyconductive member 16 and so, if the refrigerant 6 solidifies, itsexpansion in volume can be suppressed. In consequence, adhesion of thesolid refrigerant (such as solid nitrogen) onto the magazine 4,cartridges 2, and samples S can be prevented.

As shown in FIG. 2, the communication holes 19 are located in positionswhere the solid refrigerant 6 (solid nitrogen) adheres to none of themagazine 4, cartridges 2, and samples S. The size of the communicationholes 19 is so determined that the refrigerant 6 in vaporized form canpass through these holes and passage of the solidified refrigerant 6 islimited.

(2) Sample Chamber

The sample chamber 20 is next described. As shown in FIG. 1, the samplechamber 20 is a space inside an electron optical column 22. The samplechamber 20 is defined by the inner wall of the column 22. That is, itcan be said that the electron optical column 22 is a vacuum vesselhaving the sample chamber 20.

The interior of the sample chamber 20 is evacuated (i.e., gas inside thechamber is removed) by the vacuum pumping equipment (not shown). As aresult, the sample chamber 20 is maintained at vacuum or subatmosphericpressure. An ion pump, a scroll pump, a turbomolecular pump, or the likecan be used as the vacuum pumping equipment for evacuating the samplechamber 20.

A sample holder 26 has a sample holding portion 24 in its front-endportion. The sample holding portion 24 holds a sample S. The sample Sheld by the sample holding portion 24 is placed in position within thesample chamber 20 by a goniometer 28. In this example, the sampleholding portion 24 holds the sample S by holding the cartridge 2 towhich the sample S is securely held.

In the sample chamber 20, the charged particle beam (such as an electronbeam) is directed at the sample S. In the charged particle beaminstrument 100, the sample S held to the sample holding portion 24 isirradiated with the electron beam inside the sample chamber 20. Theelectron beam transmitted through the sample S is brought to focus bythe optical system. Thus, an electron microscope image is obtained. Thecomponents such as the optical system of the charged particle beaminstrument 100 will be described later in “4. Other Components of theCharged Particle Beam Instrument”.

(3) Sample Exchange Device

The sample exchange device 100A is next described. As shown in FIG. 1,this device 100A is so located that the sample exchange device 100A andthe goniometer 28 are on the opposite sides of the electron opticalcolumn 22. No restrictions are imposed on the position of the sampleexchange device 100A as long as the sample S can be exchanged in thesample chamber 20.

As shown in FIG. 1, the sample exchange device 100A is configuredincluding the sample exchange chamber 30, the partition valve 40, thevacuum pumping equipment 50, a sample holding portion 60, a coolingportion 70, a first transfer rod 80, and a second transfer rod 90.

The sample exchange chamber 30 is connected with the sample chamber 20.A partition valve 32 is mounted between the sample exchange chamber 30and the sample chamber 20. The partition valve 32 is used as a vacuumpartition between the sample exchange valve 30 and the sample chamber20. The sample exchange chamber 30 and the sample chamber 20 are placedin communication with each other by opening the partition valve 32. Thesample exchange chamber 30 and the sample chamber 20 are isolated fromeach other by closing the partition valve 32.

The sample exchange chamber 30 is a space surrounded by a vacuum vessel34. The sample exchange chamber 30 is evacuated by the vacuum pumpingequipment 50. Consequently, the sample exchange chamber 30 can bemaintained in vacuum. The sample storage portion 60 is mounted in thesample exchange chamber 30.

The sample container 10 is connected with the sample exchange chamber30. In the illustrated example, the sample container 10 is connectedwith the sample exchange chamber 30 via a connecting member 42, which inturn is connected with the sample exchange chamber 30. An O-ring 44 ismounted on the end surface of the connecting member 42. Sealing isprovided between the sample container 10 and the connecting member 42 bythe O-ring 44.

The partition valve 40 is positioned between the sample exchange chamber30 and the sample container 10 when the sample container 10 is connectedwith the sample exchange chamber 30. The partition valve 40 is used as avacuum partition between the sample exchange chamber 30 and the samplecontainer 10 (i.e., the sample-receiving space 18 a). The sampleexchange chamber 30 and the sample container 10 (i.e., thesample-receiving space 18 a) are placed in communication with each otherby opening the partition valve 40. The sample exchange chamber 30 andthe sample container 10 (i.e., the sample-receiving space 18 a) areisolated from each other by closing the partition valve 40.

The vacuum pumping equipment 50 evacuates the sample container 10. Thevacuum pumping equipment 50 can evacuate the sample container 10 underthe conditions where the sample container 10 is connected with thesample exchange device 30 and the partition valve 40 is closed. As aconsequence, the sample-receiving space 18 a and refrigerant-receivingspace 18 b of the sample container 10 are evacuated. The freezing pointof the refrigerant 6 (such as liquid nitrogen) received in therefrigerant-receiving space 18 b rises, and the refrigerant 6 can besolidified. The vacuum pumping equipment 50 can also evacuate the samplecontainer 10 while the partition valve 40 is open.

The vacuum pumping equipment 50 evacuates the sample container 10 via anexhaust tube 52. In the illustrated example, the exhaust tube 52 isconnected with the connecting member 42. A solenoid valve 54 is mountedin the exhaust tube 52.

Furthermore, the vacuum pumping equipment 50 evacuates the sampleexchange chamber 30 via an exhaust tube 56. A solenoid valve 58 ismounted in the exhaust tube 56.

An oil-sealed rotary vacuum pump, an ion pump, a scroll pump, aturbomolecular pump, or the like can be used as the vacuum pumpingequipment 50.

The sample holding portion 60 is formed in the sample exchange chamber30 and can hold a plurality of samples S. In the illustrated example,the sample holding portion 60 holds the plural cartridges 2 to which thesamples S are held. For example, the sample holding portion 60 issimilar in configuration to the magazine 4.

The sample holding portion 60 is cooled by the cooling portion 70.Accordingly, the samples S can be stored while kept cooled. The samplestorage portion 60 is made, for example, of a material of high thermalconductivity.

The cooling portion 70 cools the sample storage portion 60. The coolingportion 70 is configured including a refrigerant tank 72 (such as a tankholding liquid nitrogen) and a thermally conductive member 74 a thatthermally interconnects the tank 72 and the sample storage portion 60.The cooling portion 70 cools the thermally conductive member 74 a withthe refrigerant put in the tank 72, thus cooling the sample storageportion 60.

Furthermore, the cooling portion 70 cools the first transfer rod 80 andthe second transfer rod 90. In addition, the cooling portion 70 includesa thermally conductive member 74 b for thermally coupling together thetank 72 and the first transfer rod 80 and a thermally conductive member74 c for thermally coupling together the tank 72 and the second transferrod 90. Each of the thermally conductive members 74 a, 74 b, and 74 c ismade, for example, of copper wire.

The first transfer rod 80 carries the samples S between the samplecontainer 10 and the sample exchange chamber 30 by holding and carryingthe magazine 4. In particular, the first transfer rod 80 can grip themagazine 4 at its front end and move the magazine 4 in the Z-direction.The first transfer rod 80 conveys the magazine 4 into the sampleexchange chamber 30 by gripping the magazine 4 within the samplecontainer 10 and moving the magazine in the +Z-direction. Furthermore,the first transfer rod 80 can convey the magazine 4 (and the samples S)within the sample exchange chamber 30 into the sample container 10.

The first transfer rod 80 is cooled by the cooling portion 70.Therefore, if the first transfer rod 80 touches the cooled magazine 4,the temperature of the magazine 4 can be maintained.

The second transfer rod 90 carries the samples S between the firsttransfer rod 80 and the sample storage portion 60. In this example, thesecond transfer rod 90 transports the samples S by holding and carryingthe cartridges 2 to which the samples S are held. Specifically, thesecond transfer rod 90 can grip the cartridge 2 at its front end andmove the gripped cartridge 2 in the X-direction. The second transfer rod90 carries the cartridge 2 into the sample storage portion 60 by takingthe cartridge 2 out of the magazine 4 held by the first transfer rod 80and moving the cartridge 2 in the −X-direction. Furthermore, the secondtransfer rod 90 can take the cartridge 2 out of the sample storageportion 60 and transfer the cartridge 2 to the magazine 4 held by thefirst transfer rod 80.

Additionally, the second transfer rod 90 conveys the samples S betweenthe sample storage portion 60 and the sample chamber 20. The secondtransfer rod 90 transports the cartridges 2 into the sample chamber 20by taking the cartridges 2 out of the sample storage portion 60 andmoving the cartridges 2 in the +X-direction. In the illustrated example,the second transfer rod 90 carries the samples S into the sample holdingportion 24 within the sample chamber 20. Also, the second transfer rod90 can convey the cartridges 2 (and the samples S) from the samplechamber 20 into the sample storage portion 60.

Further, the second transfer rod 90 conveys the samples S between thesample chamber 20 and the first transfer rod 80. The second transfer rod90 transports the cartridges 2 to the first transfer rod 80 by takingthe cartridges 2 out of the sample chamber 20 (sample holding portion24) and moving the cartridges in the −X-direction. The second transferrod 90 can convey the cartridges 2 (and the samples S) from the firsttransfer rod 80 into the sample chamber 20.

The second transfer rod 90 is cooled by the cooling portion 70 and,therefore, if this rod 90 touches the cooled cartridges 2, thetemperature of the cartridges 2 can be maintained.

2. Operation of the Charged Particle Beam Instrument

The operation of the charged particle beam instrument 100 is nextdescribed by referring to FIGS. 5-11. In particular, a method ofintroducing the samples S from the sample container 10 into the samplechamber 20, a method of returning the samples S from the sample chamber20 into the sample container 10, and a method of using the samplestorage portion 60 are described. It is now assumed that liquid nitrogenis used as the refrigerant 6.

(1) Introduction of Samples into the Sample Chamber

The method of introducing the samples S from the sample container 10into the sample chamber 20 is first described.

As shown in FIG. 3, a cooled sample S is securely held to the cartridge2 by the anchoring member 3.

Then, as shown in FIG. 4, as many cartridges 2 to which respectivesamples S are securely attached as needed are mounted to the magazine 4.

As shown in FIG. 2, the magazine 4 to which the cartridges 2 areattached is received into the sample-receiving space 18 a of the samplecontainer 10 previously cooled by the refrigerant 6. The pouredrefrigerant 6 flows into the refrigerant-receiving space 18 b formed inthe bottom of the sample container 10 through the communication holes 19in the thermally conductive member 16 of the sample container 10 andstays in this space 18 b.

Then, the cover portion 14 of the sample container 10 is closed toprevent outside air containing moisture from entering the samplecontainer 10. Under this condition, the sample container 10 is conveyedinto the sample exchange device 100A. By receiving the samples S in thesample container 10 and conveying the container together with thesamples in this way, the samples S can be conveyed while cooling thesamples S such that ice contamination (such as crystalline ice or frost)does not adhere to the surfaces of the samples S.

Then, as shown in FIG. 1, the sample container 10 is mounted to thesample exchange device 100A. In particular, the cover portion 14 of thesample container 10 is removed, and the sample container 10 is attachedto the connecting member 42. The sample container 10 is connected withthe sample exchange chamber 30 via the partition valve 40. At this time,the partition valve 40 is closed. Sealing is provided between theconnecting member 42 and the sample container 10 by the O-ring 44.

In the sample exchange device 100A, the interior of the sample exchangechamber 30 has been previously evacuated by the vacuum pumping equipment50 and maintained in vacuum. That is, the solenoid valve 58 is keptopen. The first transfer rod 80, second transfer rod 90, and samplestorage portion 60 are always cooled by the cooling portion 70. Thepartition valve 32 is kept closed.

When the sample container 10 is mounted, the solenoid valve 54 is openedand the interior of the sample container 10 is evacuated. The solenoidvalve 54 may be operated either manually or automatically.

When the interior of the sample container 10 is evacuated, the freezingpoint of the refrigerant 6 in the refrigerant-receiving space 18 b risesand thus the refrigerant becomes solidified. At this time, solidparticles of the refrigerant (such as solid nitrogen) deposit and so therefrigerant 6 expands in volume. However, in the sample container 10,the refrigerant 6 is surrounded by the thermally conductive member 16.Therefore, if the refrigerant 6 solidifies, expansion of the volume canbe suppressed. Adhesion of the solid refrigerant (such as solidnitrogen) to the magazine 4, cartridges 2, and samples S can beprevented.

As shown in FIG. 5, after the interior of the sample container 10 isevacuated and the solenoid valve 54 is closed, the partition valve 40 isopened. At this time, the refrigerant 6 in the sample container 10 is insolidified form. Therefore, if the refrigerant 6 is left in thecontainer 10, deterioration of the degree of vacuum in the sampleexchange chamber 30 can be suppressed.

As shown in FIG. 6, the magazine 4 is gripped by the first transfer rod80, the rod 80 is moved in the +Z-direction, and the magazine 4 iscarried into the sample exchange chamber 30 from inside the samplecontainer 10. The partition valve 40 is then closed.

As shown in FIG. 7, one cartridge 2 is taken out of the magazine 4 heldby the first transfer rod 80, using the second transfer rod 90. Thepartition valve 32 is opened. The first transfer rod 80 is moved in the+X-direction. The cartridge 2 and the sample S are introduced into thesample chamber 20. The cartridge 2 is held to the sample holding portion24.

This permits the sample S to be introduced from the sample container 10into the sample chamber 20.

Then, as shown in FIG. 8, the second transfer rod 90 is returned to itsoriginal position, the partition valve 32 is closed, and the sample S isstarted to be observed.

(2) Takeout of Sample

Then, an operation for taking out the sample S from the sample chamber20 and returning it into the sample container 10 is next described.

As shown in FIG. 7, the partition valve 32 is opened. Then, onecartridge 2 and the sample S held to the sample holding portion 24 aregripped by the second transfer rod 90.

As shown in FIG. 6, the second transfer rod 90 gripping the cartridge 2is moved in the −X-direction to convey the cartridge 2 from the samplechamber 20 into the sample exchange chamber 30. The partition valve 32is then closed. Subsequently, the cartridge 2 gripped by the secondtransfer rod 90 is attached to the magazine 4 gripped by the firsttransfer rod 80.

Then, the solenoid valve 54 is opened. The interior of the samplecontainer 10 is evacuated to solidify the refrigerant 6. The solenoidvalve 54 is closed and then the partition valve 40 is opened. At thistime, the refrigerant 6 inside the sample container 10 is in solidifiedform and so deterioration of the degree of vacuum in the sample exchangechamber 30 can be suppressed even if the refrigerant 6 is left in thecontainer 10.

As shown in FIG. 5, the first transfer rod 80 gripping the magazine 4 ismoved in the −Z-direction to carry the magazine 4 from the sampleexchange chamber 30 into the sample container 10. Then, the partitionvalve 40 is closed.

In this way, the sample S can be returned from the sample chamber 20into the sample container 10.

After being brought back to atmospheric pressure by vaporization of therefrigerant 6 and supply of nitrogen gas, the sample container 10 isremoved from the sample exchange device 100A and the cover portion 14 isclosed.

(3) Use of the Sample Holding Portion

A method of using the sample storage portion 60 is next described. Thereare two cases. In one case, a sample S already observed is kept in thesample storage portion 60. In the other case, a sample S is conveyedfrom the sample storage portion 60 into the sample container 10.

As shown in FIG. 7, after observation of the sample S is finished, thepartition valve 32 is opened. Then, one cartridge 2 and the sample Sheld in the sample holding portion 24 are gripped by the second transferrod 90.

As shown in FIG. 9, the second transfer rod 90 gripping the cartridge 2is moved in the −X-direction to convey the cartridge 2 from the samplechamber 20 into the sample exchange chamber 30. Then, the partitionvalve 32 is closed. Subsequently, the cartridge 2 gripped by the secondtransfer rod 90 is attached to the sample storage portion 60. In theillustrated example, the sample storage portion 60 can be placed in arange where the second transfer rod 90 can move the cartridge 2 (and thesample S) by moving the sample storage portion 60 in the −Z-direction.

As shown in FIG. 10, the sample storage portion 60 is returned to itsoriginal position. That is, the sample storage portion 60 is moved intoa position where the operation of the second transfer rod 90 is nothindered.

In this way, each sample S which has been already observed can be keptin the sample storage portion 60.

Where a sample S stored in the sample storage portion 60 is introducedinto the sample chamber 20, a procedure opposite to the foregoingprocedure is adopted.

A case in which a sample S is conveyed from the sample storage portion60 into the sample container 10 is next described.

As shown in FIG. 9, the sample storage portion 60 is moved in the−Z-direction, and the cartridge 2 attached to the sample storage portion60 is gripped by the second transfer rod 90.

As shown in FIG. 11, the second transfer rod 90 gripping the cartridge 2is moved in the +X-direction to mount the cartridge 2 to the magazine 4held by the first transfer rod 80.

As shown in FIG. 5, the partition valve 40 is opened. The first transferrod 80 gripping the magazine 4 is moved in the −Z-direction to carry themagazine 4 from the sample exchange chamber 30 into the sample container10. Then, the partition valve 40 is closed.

Consequently, the sample S can be returned from the sample storageportion 60 into the sample container 10.

After being brought back to atmospheric pressure by vaporization of therefrigerant 6 and supply of nitrogen gas, the sample container 10 isremoved from the sample exchange device 100A. The cover portion 14 isclosed.

Where the sample S is conveyed from the sample container 10 to thesample storage portion 60, a procedure opposite to the foregoingprocedure is followed.

The charged particle beam instrument 100 and the sample container 10have the following features.

In the charged particle beam instrument 100, the sample container 10 canbe connected with the sample exchange chamber 30 via the partition valve40. The container 10 is evacuated by the vacuum pumping equipment 50while the partition valve 40 is closed. Therefore, the partition valve40 can be opened after the interior of the sample container 10 isevacuated and the refrigerant 6 is solidified. Consequently, if therefrigerant 6 is left in the container 10, the sample S can beintroduced into the sample exchange chamber 30 from the sample container10. This permits the sample S to be introduced into the sample chamber20 easily via the sample exchange chamber 30.

FIG. 12 shows the configuration of a known charged particle beaminstrument, 1000, providing a reference. In this instrument 1000, asample container 10 cannot be evacuated if a partition valve 40 isclosed. Therefore, when a sample S is introduced into a sample chamber20 from the sample container 10, the interior of a sample exchangechamber 30 is returned to atmospheric pressure, for example, usingnitrogen gas. Then, the partition valve 40 is opened to vaporizerefrigerant 6 (such as liquid nitrogen) inside the sample container 10.After the refrigerant 6 is fully vaporized, one sample S inside thesample container 10 is introduced into the sample exchange chamber 30with a first transfer rod 80. The partition valve 40 is then closed. Theinterior of the sample exchange chamber 30 is evacuated and then apartition valve 32 is opened. The sample S is introduced into the samplechamber 20. In this known charged particle beam instrument 1000, thesample container 10 does not have any thermally conductive member likethe thermally conductive member 16 shown in FIG. 2. A magazine 4 and therefrigerant 6 are accommodated in the same space.

In this way, in the known charged particle beam instrument 1000providing a reference, the sample exchange chamber 30 must be brought toatmospheric pressure in order to introduce the sample S from the samplecontainer 10 into the sample chamber 20. Similarly, in this knowninstrument 1000, the sample exchange chamber 30 must be brought toatmospheric pressure in order to return the sample S from the samplechamber 20 into the sample container 10. In contrast, in the inventivecharged particle beam instrument 100, the sample S can be introducedinto the sample exchange chamber 30 from the sample container 10 withoutbringing the sample exchange chamber 30 to atmospheric pressure if therefrigerant 6 is left in the sample container 10.

Furthermore, in the inventive charged particle beam instrument 100, thesample S can be introduced from the sample container 10 into the samplechamber 20 and thence returned into the sample container 10 withoutbringing the sample exchange chamber 30 to atmospheric pressure, i.e.,the vacuum state is maintained. Therefore, the sample S cooled undervacuum can be stored in the sample storage portion 60. Consequently, thesample S can be kept at low temperatures in the sample storage portion60.

In the known charged particle beam instrument 1000 shown in FIG. 12, ifthe sample storage portion 60 reaches atmospheric pressure when thesample S is introduced into the sample chamber 20, the effects of vacuuminsulation are not obtained. It is difficult to maintain the sample Sstored in the sample storage portion 60 at low temperatures at alltimes.

In the inventive charged particle beam instrument 100, the samplecontainer 10 has the thermally conductive member 16 that isolates thesample-receiving space 18 a accommodating the samples S therein and therefrigerant-receiving space 18 b accommodating the refrigerant 6 thereinfrom each other. The thermally conductive member 16 is provided with thecommunication holes 19 that place the sample-receiving space 18 a andthe refrigerant-receiving space 18 b in communication with each other.This can prevent adhesion of solid refrigerant (such as solid nitrogen)onto the magazine 4, cartridges 2, and samples S.

The charged particle beam instrument 100 includes: the sample storageportion 60 formed in the sample exchange chamber 30 and capable ofholding the samples S; and the cooling portion 70 for cooling the samplestorage portion 60. Consequently, the samples S can be stored whilecooled. Furthermore, in the charged particle beam instrument 100, thesamples S cooled under vacuum can be stored in the sample storageportion 60 as described previously. This permits the sample S to be keptat low temperatures in the sample storage portion 60. Moreover, whereplural samples S are observed, the labor to exchange the samples S canbe alleviated.

The charged particle beam instrument 100 includes the first transfer rod80 for transferring each sample S between the sample container 10 andthe sample exchange chamber 30 and the second transfer rod 90 fortransferring each sample S between the first transfer rod 80 and thesample storage portion 60. Consequently, each sample S can be conveyedfrom the sample container 10 to the sample storage portion 60, and viceversa.

In the charged particle beam instrument 100, the second transfer rod 90further conveys the sample S between the sample storage portion 60 andthe sample chamber 20. Consequently, the sample S can be conveyed eitherfrom the sample container 10 or from the sample storage portion 60 intothe sample chamber 20, and vice versa.

In the charged particle beam instrument 100, the refrigerant 6 isevacuated by the vacuum pumping equipment 50 and solidifies. As aconsequence, as described previously, the sample S can be easilyintroduced into the sample chamber 20. The refrigerant 6 may be any oneof liquid nitrogen, liquid methane, liquid ethane, and liquid butane.Thus, the refrigerant 6 can be solidified by evacuating the samplecontainer 10.

The sample container 10 has the thermally conductive member 16 thatpartitions the sample-receiving space 18 a accommodating each sample Stherein and the refrigerant-receiving space 18 b accommodating therefrigerant 6 therein from each other. The thermally conductive member16 is provided with the communication holes 19 that place thesample-receiving space 18 a and the refrigerant-receiving space 18 b incommunication with each other. Consequently, when the sample container10 is evacuated and the refrigerant 6 is solidified, adhesion of thesolid refrigerant (such as solid nitrogen) onto the magazine 4,cartridges 2, and samples S can be prevented.

4. Other Components of the Charged Particle Beam Instrument

The components of the charged particle beam instrument 100 other thanthe sample exchange device 100A are next described by referring to FIG.13, which shows the configuration of the charged particle beaminstrument 100. In FIG. 13, the sample exchange device 100A isschematically shown for the sake of convenience.

As shown in FIG. 13, the charged particle beam instrument 100 isconfigured including a charged particle beam source 110, an opticalsystem 120, and an imaging device 130.

The charged particle beam source 110 emits a charged particle beam (suchas an electron beam) EB. A well-known electron gun can be used as thecharged particle beam source 110. No restrictions are placed on theelectron gun used as the charged particle beam source 110. For example,a thermionic electron gun, thermal field-emission electron gun, or coldfield emission electron gun can be used.

The optical system 120 is configured including an illumination lens 122for directing the electron beam EB at a sample S, an objective lens 124constituting an imaging system for focusing the electron beam EBtransmitted through the sample S, an intermediate lens 126, and aprojector lens 128.

The imaging device 130 creates an electron microscope image from theelectron beam focused by the imaging system including the lenses 124,126, and 128. The imaging device 130 is configured including a CCDcamera, for example, having a two-dimensional array of solid-stateimaging elements. The imaging device 130 takes an electron microscopeimage and outputs information about this electron microscope image.

In the illustrated example, the charged particle beam instrument 100 ismounted on a pedestal 150 via vibration isolators 140.

In the above-described embodiment, the charged particle beam instrumentis a transmission electron microscope. No restrictions are placed on thecharged particle beam instrument associated with the present inventionas long as the instrument uses a charged particle beam of electrons orions. The charged particle beam instrument associated with the presentinvention may be an electron microscope (such as a scanning transmissionelectron microscope (STEM) or a scanning electron microscope (SEM)), anelectron probe microanalyzer (EPMA), a focused ion beam (FIB)instrument, an electron beam exposure system, or the like.

The present invention embraces configurations (e.g., configurationsidentical in function, method, and results or identical in purpose andadvantageous effects) which are substantially identical to theconfigurations described in connection with the above embodiment.Furthermore, the invention embraces configurations which are similar tothe configurations described in connection with the above embodimentexcept that their nonessential portions have been replaced.Additionally, the invention embraces configurations which are identicalin advantageous effects to, or which can achieve the same object as, theconfigurations described in connection with the above embodiment.Further, the invention embraces configurations which are similar to theconfigurations described in connection with the above embodiment exceptthat a well-known technique is added.

Having thus described my invention with the detail and particularityrequired by the Patent Laws, what is desired protected by Letters Patentis set forth in the following claims.

The invention claimed is:
 1. A charged particle beam instrumentcomprising: a sample container that accommodates samples and arefrigerant for cooling the samples; an evacuated sample chamber; asample exchange chamber connected with the sample chamber; a partitionvalve disposed between the sample exchange chamber and the samplecontainer; and vacuum pumping equipment for evacuating the samplecontainer; wherein the sample container can be connected by connectingmeans with the sample exchange chamber and brought into communicationwith the sample exchange chamber via the partition valve and can beevacuated by the vacuum pumping equipment while the partition valve isclosed wherein said sample container has a sample-receiving space forreceiving the samples, a liquefied gas refrigerant-receiving space forreceiving the refrigerant, and a thermally conductive member thatpartitions the sample-receiving space and the refrigerant-receivingspace from each other, and wherein the thermally conductive member isprovided with communication holes for placing the sample-receiving spaceand the refrigerant-receiving space in communication with each other,such that when said refrigerant-receiving space is evacuated by saidvacuum pumping equipment the refrigerant becomes solidified.
 2. Thecharged particle beam instrument as set forth in claim 1, wherein saidsample exchange chamber has a sample storage portion capable of holdingthe samples, and wherein there is further provided a cooling portion forcooling the sample storage portion.
 3. The charged particle beaminstrument as set forth in claim 2, further comprising a first transferrod for conveying the samples between said sample container and saidsample exchange chamber and a second transfer rod for conveying thesamples between the first transfer rod and the sample storage portion.4. The charged particle beam instrument as set forth in claim 3, whereinsaid second transfer rod further operates to convey the samples betweensaid sample storage portion and said sample chamber.
 5. The chargedparticle beam instrument as set forth in claim 1, wherein saidrefrigerant is any one of liquid nitrogen, liquid methane, liquidethane, and liquid butane.
 6. A sample container capable of beingconnected via a partition valve with a sample exchange chamber in acharged particle beam instrument, said sample container comprising: asample-receiving space for receiving samples; a refrigerant-receivingspace for receiving a refrigerant; and a thermally conductive memberthat partitions the sample-receiving space and the refrigerant-receivingspace from each other, the thermally conductive member being providedwith communication holes for placing the sample-receiving space and therefrigerant-receiving space in communication with each other such thatwhen said refrigerant-receiving space is evacuated the refrigerant issolidified.
 7. The sample container as set forth in claim 6, whereinsaid refrigerant is any one of liquid nitrogen, liquid methane, liquidethane, and liquid butane.